A Supervisory Control And Data Acquisition (SCADA) is a type of industrial control system (ICS) used to monitor and control industrial processes. The term SCADA refers to a centralized systems which are capable of monitoring and controlling entire sites, or complexes of systems spread out over large areas. Multiple Human Machine Interface (HMI) devices are linked to a Programmable Logic Controller (PLC) of the SCADA system. The HMI devices are configured to access the SCADA system's database and software programs, in order to provide trending, diagnostic data, and management information such as, scheduled maintenance procedures, logistic information and the like to a user at a remote location.
Known system architecture solutions require the PLC to be communicating with only one HMI device at a time. These systems therefore involve the PLC communicating with a single server HMI device. This server HMI device in turn communicates with the other client HMI devices. However, on failure of the server HMI device, the entire system may fail. Hence, the system may be susceptible to high risk of failure.
U.S. Publication Number 2011/0161538 discloses a method and system for implementing redundant master NIMs on a single bus in an industrial distributed I/O system for controlling selected I/O modules. Two master NIMs interoperate on a single bus, with one being the primary, active, master, and the second master in a secondary, standby, mode, ready to assume mastership of the system if the primary master is no longer active.